The invention relates to a closing unit for tools to be pressed together against opening forces having two tool carrier plates which can be displaced towards one another.
Such closing units are used in the area of reshaping technology in which the divided tool has to be kept closed against opening forces. Such opening forces which are exerted on the closed tool arise, for example, during the plastic moulding or during the internal high pressure reshaping of tubes to form hollow bodies in a desired shape.
These closing units usually consist of presses which have to comprise very large closing forces in particular in internal high pressure reshaping. For instance, presses are used in production in automobile technology, for example, for elongate hollow bodies which are manufactured via internal high pressure reshaping, which have a closing force of up to 16,000 tonnes. Such presses can have an overall height of up to 14 meters. In addition, they are expensive to purchase and to service.
It is the object of the invention to provide a closing unit of the desired kind for tools to be pressed together against opening forces which is of a simple design and an overall small size.
This object is satisfied in accordance with the invention by a closing unit of the desired kind having the features herein. Accordingly, a closing unit for tools to be pressed together against opening forces having two tool carrier plates which can be displaced towards one another has two jaws engaging over the tool carrier plates at the side in each case in a closed position while building up a bias.
A completely new concept is pursued with the present invention. Whereas, up to now, closing units for the pressing together of tools against opening forces were as a rule realised by pressing with very high closing forces, the closing unit in accordance with the invention utilises the basic idea that the forces are generally applied by rigid jaws which are pushed while building up a bias via holding regions of the tool carrier plates in the closed position, that is in the position the tools have to be held together. Since the high pressing forces no longer have to be applied, the construction size of the closing unit, and thus naturally also the total investment volume for the purchase of a corresponding closing unit can be dramatically reduced.
Advantageous aspects of the invention result from the disclosure herein.
The closing unit can be designed particularly advantageously in modular form. That is, it consists of modules of the same design which can be connected to one another, with one module consisting in each case of a base plate, two tool carrier plates which can be displaced towards one another by means of piston in cylinder arrangements and in each case two jaws which can be displaced with respect to the tool carrier plates by two piston in cylinder arrangements. The modular design makes it possible to exactly adjust the closing force of the unit to the application. For instance, a corresponding module of the closing unit can have a bias force of more than 2,000 tonnes per running meter. Depending on the length of the component to be manufactured, a corresponding number of modules can then be coupled to one another. This has a substantial advantage over the closing units designed as presses as these generally have to be designed in accordance with the longest tools to be taken up and so can be oversized for a number of applications. In contrast to this, the closing unit in accordance with the invention can always be matched to the application with a modular design.
The jaws are advantageously formed in a U shape, with the limbs being able to be travelled out to build up the bias on the movement towards the tool carrier plate and on the engaging over of the tool carrier plates at the side onto wedges extending at an incline. The required bias, with which the tool parts are pressed together over the tool carrying plates carrying these, can here be applied by a correspondingly lateral displacement by comparatively small-sized piston in cylinder arrangements.
The wedges arranged at the tool carrier plates can consist of a separately replaceable component made of an abrasion-resistant material. These are wear parts which can accordingly be easily replaced.
At the same time, the contact surface inside the limbs of the jaws can likewise consist of replaceable parts made of an abrasion-resistant material, with the contact surfaces on the jaw side being made of rails approximately semi-circular in cross-section, with these semi-circular rails being mounted in correspondingly semi-circular grooves within the jaws.
In accordance with a preferred embodiment, a lower tool carrier plate can be fixedly secured to the base plate, while an upper tool carrier plate can be travelled over four symmetrically arranged piston in cylinder arrangements, with the piston in cylinder arrangements being likewise secured to the base plate at the one end and to corresponding crossbeams, in which the upper tool carrier plate is received, at the other end. The upper tool carrier plate can be travelled over the four symmetrically arranged piston in cylinder arrangements in a perpendicular manner with respect to the lower tool carrier plate.
In accordance with one embodiment, the jaws can be displaceably guided over bearings on the base plate, with these being movable with respect to the tool carrier plates via piston in cylinder arrangements connected to the lower tool carrier plate at the one end and via piston in cylinder arrangements which can be coupled into the upper tool carrier plate when this is lowered at the other end.
Alternatively to this, in another variant, the jaws can be displaceable with respect to the tool carrier plates via at least one piston in cylinder unit which is mounted in a bearing block arranged on the base plate.
One or two bias membrane(s) which can be acted on by hydraulic fluid can be arranged between the tool carrier plate and the part of the tool fixedly clamped in the tool carrier plate in order to apply the corresponding closing force, with delivery openings for the hydraulic fluid being provided inside the tool carrier plate such that on the pressing in of hydraulic fluid, the membrane is deformed in the direction towards the clamped work part and thus additionally works against the opening forces.